Cartridge new or used ?

Disgusting.

What is it with all the wet necks and used cartridges!
Use your head and common sense when shopping and you will be fine. Remember that one, common sense, that's right the least common of all senses nowadays it seems!
I have bought and sold many used cartridges here and on eBay.
There still are a LOT of very honest people in this hobby.
How else is one to try and acquire and use some of the better vintage mm carts apart from taking the plunge and buying used?

If you do not want to take a chance personally that's fine but do NOT denigrate the process as a whole!

There are many dishonest people on fleabay and you have no way of telling before you commit to purchasing, because fleabay protects its insider club sellers by doctoring the feedback info that’s published. 

Why would you go vintage when brand-new, I’m-abused Audio-Technica Micro-Line cartridges are available everywhere at reasonable prices? (Thanks Chakster) I prefer a known commodity, and it’s worked out superbly with my VM540ML cartridges. Heck, I even use a VM540ML stylus on my VM610 mono cartridge. You just can’t go wrong with them. 

Sleepwalker
You definitely have some deep rooted trust issues. And your comments about doctored feedback is highly amusing.
But to each their own, I have no problem with anybody who prefers to go the route you advocate but please do not harbour malice to those who DO decide to buy used and save a fortune potentially.
One of my friends just bought a Koetsu Rosewood Signature Platinum for approx 17% of new retail.......